1. Field of the Invention
The present invention relates to an image forming device.
2. Description of the Related Art
In copiers or other image forming devices of the related art, once image data for forming an image are all stored in a memory, image forming processing is performed on the stored image data. In this case, in order to realize functions of processing data equivalent to plural pages (for example, a sorting function), it is necessary to have a storage size for storing the data equivalent to plural pages. However, for an image forming device having a small storage size, the number of pages able to be stored is limited, and when reading a manuscript, capacity overflow may occur, which may interrupt the image forming process. For this reason, it is difficult to effectively realize the sorting function, and the needs of users cannot be satisfied.
In order to solve this problem, various developments have been made in the related art to improve effective utilization of the storage size of an image forming device having a small storage size.
For example, Japanese Laid Open Patent Application No. 2003-87538 (hereinafter, referred to as “reference 1”) discloses a technique of a communication device which confirms the residual memory size while storing image data, stops data reading operations before the memory is full, and waits for a certain period until the residual memory size increases. Specifically, before reading data from each page, the residual size of a page-memory is compared to a preset value, and when the page-memory residual size is less than the preset value the reading operations are stopped until the residual size of the page-memory becomes larger than the preset value; then, when the residual size of the page-memory becomes larger than the preset value, alternatively, when the residual size of the page-memory is still less than the preset value even after a preset time period elapses, the reading operations are resumed for memory transmission reservation. Therefore, when storing the transmitted data in a memory, it is possible to prevent termination of operations due to errors caused when the memory becomes full. Thus, it is possible to reduce the workload of operators.
However, in the technique disclosed in reference 1, since the system continues to wait as long as the residual memory size is less than the preset value, for example, during copying operations, a problem may occur that the copying operations may be halted if the memory does not have a sufficient vacancy for a long time, namely, the system is trapped by the condition that the memory does not have a vacancy sufficiently larger than the preset value, and the system is halted.